Filtration device

ABSTRACT

A protruding portion is formed on an inner tube inserted into a hollow portion of a filter medium so as to protrude upward from a flange portion. The flange portion having a substantially circular plate shape is disposed on a lower side of a second plate. A recessed portion into which the protruding portion is inserted is formed on a surface on a lower side of the second plate provided so as to cover an opening at a lower end of the filter medium.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of International Patent Application No. PCT/JP2019/000085 filed on Jan. 7, 2019, which claims priority to Japanese Patent Application No. 2018-005227 filed on Jan. 16, 2018, the entire contents of which are incorporated by reference.

TECHNICAL FIELD

The present invention relates to a filtration device.

BACKGROUND ART

Patent Document 1 discloses a filter structure in which lid-side protruding portions protruding toward an end surface of a filter element are formed on a lower surface of a lid member, and a filter-side recessed portion having a shape fitting to the lid-side protruding portions is formed in the filter element.

CITATION LIST Patent Document

Patent Document 1: Japanese Registered Utility Model No. 3185612

In Patent Document 1, by cutting the lid-side protruding portions and the filter-side recessed portion of a component in which the lid-side protruding portions and the filter-side recessed portion are formed (so-called a genuine product), a component in which the lid-side protruding portions or the filter-side recessed portion are not formed (so-called a non-genuine product) becomes usable. Use of the non-genuine product possibly results in deterioration of filtration performance and a leakage of liquid.

SUMMARY OF INVENTION

One or more embodiments of the present invention provide a filtration device that securely prevents use of a component other than a genuine product (a component of a so-called non-genuine product).

A filtration device according to the present invention, for example, includes a filter element, a filter case, and a lid member. The filter element includes a filter medium, a first plate, and a second plate. The filter medium has a hollow substantially cylindrical shape with openings at both ends. The first plate is provided so as to cover the opening at an upper end of the filter medium. The second plate is provided so as to cover the opening at a lower end of the filter medium. The filter case having a bottomed substantially cylindrical shape is internally provided with the filter element. The lid member is provided so as to cover an opening at an upper end of the filter case. The filter element includes an inner tube inserted into a hollow portion of the filter medium. The second plate has a hole into which the inner tube is inserted. The inner tube includes a flange portion and a protruding portion. The flange portion having a substantially circular plate shape is disposed on a lower side of the second plate. The protruding portion is formed on the flange portion so as to protrude upward from the flange portion. A recessed portion into which the protruding portion is inserted is formed on a surface on a lower side of the second plate.

According to the filtration device according to one or more embodiments of the present invention, the protruding portion is formed on the inner tube inserted into the hollow portion of the filter medium so as to protrude upward from the flange portion. The flange portion having the substantially circular plate shape is disposed on the lower side of the second plate. The recessed portion into which the protruding portion is inserted is formed on the surface on the lower side of the second plate provided so as to cover the opening at the lower end of the filter medium. In contrast to a genuine product including the protruding portion and the recessed portion, in a non-genuine product not including the protruding portion or the recessed portion, the filter element cannot be inserted up to a correct position and therefore the filtration device cannot be used. By thus providing the protruding portion and the recessed portion in the genuine product, use of a component other than the genuine product (so-called a component of the non-genuine product) is securely prevented.

Here, the filtration device may be configured as follows. The first plate includes a first tubular portion having a substantially cylindrical shape. The first tubular portion protrudes toward the lid member with the filter element inserted into the filter case. The lid member includes a second tubular portion and ribs. The second tubular portion is inserted into a hollow portion of the first tubular portion. When the second tubular portion is inserted into the first tubular portion, the ribs are provided along an outer circumferential surface of the first tubular portion. A position of the first tubular portion overlaps with a position of the rib in plan view. A second recessed portion is formed on the rib such that a part where the rib overlaps with the first tubular portion is cut out. With the lid member attached to the first plate, a bottom surface of the second recessed portion is adjacent to a distal end of the first tubular portion. In contrast to the genuine product including the second recessed portion, in a non-genuine product not including the second recessed portion, the distal ends of the ribs abut on a distal end of the first tubular portion and therefore the filter element cannot be inserted up to the correct position and the filtration device cannot be used. This securely prevents the use of the component of the non-genuine product.

Here, the filtration device may be configured as follows. The first tubular portion includes a small-diameter portion provided on a distal end side and a large-diameter portion provided on a base side. The small-diameter portion has an outer diameter smaller than an outer diameter of the large-diameter portion. The second recessed portion is formed on the rib such that a position of the rib overlaps with a position of the small-diameter portion and a part where the rib overlaps with the small-diameter portion is cut out in plan view. With the lid member attached to the first plate, the ribs are disposed along an outer circumferential surface of the small-diameter portion and distal ends of the ribs are adjacent to a planar portion formed between the small-diameter portion and the large-diameter portion. In contrast to the genuine product including the second recessed portion, in a non-genuine product not including the second recessed portion, the distal ends of the ribs abut on a distal end of the small-diameter portion and therefore the filter element cannot be inserted up to the correct position and the filtration device cannot be used. This securely prevents the use of the component of the non-genuine product.

Here, the filtration device may be configured as follows. The first tubular portion includes projections protruding outward in a radial direction. The ribs are provided with notches. With the lid member attached to the first plate, the second tubular portion is inserted into the first tubular portion and the projections are inserted into the notches. This makes it difficult to produce the component of the non-genuine product, and use of the component of the non-genuine product can be more effectively prevented.

Here, the protruding portion may have a substantially cylindrical shape. Thus configuring the protruding portion so as to have a simple shape facilitates the manufacturing.

One or more embodiments of the present invention is capable of preventing the use of a component other than the genuine product (a component of a so-called non-genuine product).

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view illustrating an overview of a filtration device 1 according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating an overview of the filtration device 1.

FIG. 3 is a partially enlarged view of the filtration device 1 and a partially cutaway view.

FIG. 4 is a perspective view of a lid member 20.

FIG. 5 is a perspective view of a filter element 30.

FIG. 6 is a cross-sectional perspective view of the filtration device 1 and a partially enlarged view.

FIG. 7 is a cross-sectional perspective view of a filter case 10 and an inner tube 31 and a partially enlarged view.

FIG. 8 is a perspective view of the filter element 30 and a partially enlarged view.

FIG. 9 is a diagram illustrating an overview of a first imitation attachment prevention structure 50A included in a filtration device 2.

FIG. 10 is a cross-sectional view on a surface P in FIG. 9 .

FIG. 11 is a diagram illustrating an overview of a modification in which a small-diameter portion 34 g is not used.

FIG. 12 is a diagram illustrating an overview of a third imitation attachment prevention structure 52 included in a filtration device 3.

DESCRIPTION OF EMBODIMENTS

Hereinafter, with reference to the drawings, detailed description will be made on embodiments of the present invention.

First Embodiment

FIG. 1 is a perspective view illustrating an overview of a filtration device 1. The filtration device 1 removes, for example, dust contained in a liquid, such as an oil and water, using a filter and mainly includes a filter case 10, a lid member 20, and a filter element 30 (see, for example, FIG. 2 ).

The lid member 20 includes an inflow port 21 and an outflow port 22. The inflow port 21 flows a liquid before filtration in an internal space formed by the filter case 10 and the lid member 20. The outflow port 22 flows out a liquid after filtration.

An indicator 40 is provided on the lid member 20. The indicator 40 measures a pressure difference inside the filter case 10 using a reed switch (not illustrated) provided inside the indicator 40 and indicates the measurement result by turning on/off a lamp (not illustrated). Note that the indication of the measurement result is not limited to the turning on/off of the lamp. For example, the measurement result may be displayed on a display unit (for example, a liquid crystal panel).

FIG. 2 is a cross-sectional view illustrating an overview of the filtration device 1. The filter case 10 is a substantially bottomed cylindrical member made of metal or resin and has one end (here, a lower end) that is substantially closed and the open other end. The substantially closed lower end of the filter case 10 is a bottom surface 11.

A hole 12 is formed in the bottom surface 11 of the filter case 10, and a drain (not illustrated) is provided in the hole 12. The drain may be omitted.

The filter case 10 has a substantially cylindrical side surface 13. The side surface 13 has a lower end connected to the bottom surface 11. An upper end of the side surface 13 is an open end 14. An internal thread portion 15 is formed on an inner circumferential surface of the side surface 13 in the vicinity of the open end 14.

The lid member 20 is a member having a substantially bottomed cylindrical shape and made of metal. The lid member 20 includes an attachment portion 23 having a substantially cylindrical shape formed to protrude from the bottom surface to a lower side (−z side). An external thread portion 24 is formed on an outer circumferential surface of the attachment portion 23.

The open end 14 of the filter case 10 is attached to the lid member 20. Screwing the external thread portion 24 into the internal thread portion 15 attaches the lid member 20 to the filter case 10. The lid member 20 is thus provided so as to cover the open end 14 of the filter case 10. Note that the lid member 20 is provided such that its bottom surface is located on the upper side (+z side).

Thus connecting the open end of the lid member 20 and an open end of the filter case 10 forms a space into which the filter element 30 is inserted is formed inside the filtration device 1.

A sealing member (for example, an O-ring) (not illustrated) is provided between the filter case 10 and the lid member 20. The sealing member provides sealing to avoid a liquid to leak outside from between the filter case 10 and the lid member 20.

The lid member 20 includes a fitting cylinder 25 having a substantially cylindrical shape formed to protrude from the bottom surface to the lower side (−z side). The fitting cylinder 25 is formed inside the attachment portion 23. The fitting cylinder 25 is inserted into an inside of a tubular portion 34 c (described in detail later) of a plate 34 (described in detail later). The fitting cylinder 25 constitutes a structure for preventing imitation attachment (a first imitation attachment prevention structure, described in detail later).

The filter case 10 is internally includes the filter element 30 and an inner tube 31. The filter element 30 mainly includes a filter medium 32 and plates 33, 34 provided on both ends of the filter medium 32.

When the lid member 20 is attached to the filter case 10, the filter element 30 and the inner tube 31 are held in the internal space formed by the filter case 10 and the lid member 20.

The inner tube 31 is a member having a hollow substantially cylindrical shape and formed of a material with high corrosion resistance (resin in the present embodiment). The inner tube 31 is provided inside the filter case 10 and inserted an inner circumferential surface of the filter medium 32. The substantially cylindrical part inserted into the inner circumferential surface of the filter medium 32 is a tubular portion 31 a. A large number of holes 31 d through which hydraulic oil passes are formed on the entire surface of the tubular portion 31 a.

The filter medium 32 has a hollow substantially cylindrical shape having a thickness in the radial direction thereof. The filter medium 32 is formed by pleating a sheet-like filter paper using, for example, synthetic resin and paper, and connecting both ends of the pleated filter paper to round in a cylindrical shape. The filter medium 32 is provided on the outer side of the inner tube 31.

The plates 33, 34 are substantially plate-shaped members, and are formed using a material with high corrosion resistance (resin in the present embodiment). The plate 33 is provided on the lower side of the filter medium 32, and the plate 34 is provided on the upper side of filter medium 32.

The plates 33, 34 include plate-like portions 33 a, 34 a having a substantially circular plate shape that cover end surfaces of the filter medium 32. Holes 33 b, 34 b into which the inner tube 31 is inserted are formed in the plate-like portions 33 a, 34 a, respectively. In plan view (as viewed in the z-direction), the holes 33 b, 34 b have a size substantially same as a size of a hollow portion of the filter medium 32.

The inner tube 31 includes a flange portion 31 b having a substantially circular plate shape disposed on a lower side of the plate-like portion 33 a and a protruding portion 31 c formed so as to protrude upward from the flange portion 31 b. A recessed portion 33 c into which the protruding portion 31 c is inserted is formed on a surface on a lower side of the plate-like portion 33 a. The protruding portion 31 c and the recessed portion 33 c constitute a structure for preventing imitation attachment (a second imitation attachment prevention structure, described in detail later).

The tubular portion 34 c having a substantially cylindrical shape is formed on the plate-like portion 34 a. The tubular portion 34 c protrudes on the opposite side of the filter medium 32 when the plate 34 is provided on the filter medium 32. In other words, the tubular portion 34 c protrudes toward the lid member 20 with the filter element 30 inserted into the filter case 10.

Projections 34 d are formed in the vicinity of a distal end 34 e of the tubular portion 34 c. The projections 34 d constitute a structure for preventing imitation attachment (the first imitation attachment prevention structure, described in detail later).

The fitting cylinder 25 is inserted into the tubular portion 34 c. In the vicinity of the distal end 34 e of the tubular portion 34 c, an inner circumferential surface 34 f opposed to the fitting cylinder 25 when the fitting cylinder 25 is inserted is provided. When the fitting cylinder 25 is inserted into the tubular portion 34 c, a sealing member 41 provided on the inner circumferential surface 34 f elastically deforms and closely contacts the fitting cylinder 25 and the tubular portion 34 c. As a result, the filter element 30 is provided on the lid member 20.

FIG. 3 is a partially enlarged view of the filtration device 1 and a partially cutaway view. A first imitation attachment prevention structure 50 mainly includes ribs 25 a formed on the fitting cylinder 25 and the projections 34 d formed on the tubular portion 34 c.

FIG. 4 is a perspective view of the lid member 20. A flange portion 25 b having a substantially circular plate shape is provided in the vicinity of a lower end of the fitting cylinder 25 (see FIG. 3 ) so as to protrude outward in the radial direction. A distal end side with respect to the flange portion 25 b of the fitting cylinder 25 is an insertion portion 25 c inserted into a hollow portion of the tubular portion 34 c (see FIG. 3 ).

A plurality of the ribs 25 a substantially parallel to the insertion portion 25 c are formed on the flange portion 25 b. The rib 25 a is a substantially plate-shaped member and protrudes in the same direction as the insertion portion 25 c. Each of the plurality of ribs 25 a are a part of a substantially-cylindrical-shaped rib and are separately provided. Between the adjacent ribs 25 a and 25 a are notches 25 d into which the projections 34 d are inserted. In plan view, the plurality of ribs 25 a and notches 25 d are disposed uniformly.

FIG. 5 is a perspective view of the filter element 30. A plurality of the projections 34 d having a substantially plate shape protruding outward in the radial direction are formed on the tubular portion 34 c. Each of the plurality of projections 34 d are a part of a flange having a substantially circular plate shape and are separately provided. In plan view, the plurality of projections 34 d are disposed uniformly.

In the present embodiment, while the projections 34 d are provided along the distal end 34 e, the projections 34 d only need to be provided in the vicinity of the distal end 34 e. For example, the projections 34 d may be provided slightly below the distal end 34 e. However, it is desirable that a position in a height direction of the projection 34 d overlaps with the inner circumferential surface 34 f.

The description will now return to FIG. 3 . When the insertion portion 25 c (see FIG. 4 ) is inserted into the tubular portion 34 c and the lid member 20 is attached to the plate 34, the ribs 25 a are provided along the outer circumferential surface of the tubular portion 34 c. In addition, when the insertion portion 25 c (see FIG. 4 ) is inserted into the tubular portion 34 c and the lid member 20 is attached to the plate 34, the projection 34 d is inserted between the rib 25 a and the rib 25 a.

By disposing the ribs 25 a and the projections 34 d in this manner, the projections 34 d do not interfere with the ribs 25 a, and the lid member 20 can be pushed to the plate 34 until the distal end 34 e (see FIG. 5 ) of the tubular portion 34 c abuts on the flange portion 25 b.

FIG. 6 is a cross-sectional perspective view of the filtration device 1 and a partially enlarged view. A second imitation attachment prevention structure 51 mainly includes the protruding portion 31 c formed on the inner tube 31 and the recessed portion 33 c formed on the plate 33.

FIG. 7 is a cross-sectional perspective view of the filter case 10 and the inner tube 31 and a partially enlarged view. The inner tube 31 includes a protruding portion 31 e formed so as to protrude downward (in the −z-direction) from the flange portion 31 b having a substantially circular plate shape. When an external thread 31 f formed on an outer circumferential surface of the protruding portion 31 e is screwed into an internal thread portion 12 a formed in the hole 12, the inner tube 31 is attached to the filter case 10. With the inner tube 31 attached to the filter case 10, the flange portion 31 b abuts on the bottom surface 11.

The protruding portion 31 c that protrudes upward (in the +z-direction) from the flange portion 31 b is formed on the flange portion 31 b. Here, the protruding portion 31 c has a simple shape and is a rib having a substantially cylindrical shape for ease of manufacturing.

FIG. 8 is a perspective view of the filter element 30 and a partially enlarged view. The plate 33 includes a tubular portion 33 d formed on a lower side of the plate-like portion 33 a. The recessed portion 33 c is formed in a surface 33 e of the lower side of the tubular portion 33 d. Here, the recessed portion 33 c is a substantially circular groove.

The description will now return to FIG. 6 . The filter element 30 is inserted into the filter case 10 so that the inner tube 31 is inserted into the hollow portion of the filter medium 32. Because the protruding portion 31 c is inserted into the recessed portion 33 c, the filter element 30 is inserted until the surface 33 e abuts on an upper surface of the flange portion 31 b.

When the surface 33 e is inserted until abutting on the upper surface of the flange portion 31 b, a sealing member 42 provided in the hole 33 b elastically deforms and closely contacts an outer circumferential surface 31 g of the inner tube 31 and an inner circumferential surface of the tubular portion 33 d. As a result, the filter element 30 is provided to the inner tube 31.

Next, an operation of the filtration device 1 will be described. The arrows in FIG. 2 indicate a flow of a liquid. The liquid that has flowed from the inflow port 21 is introduced between the filter case 10 and the filter element 30. After that, the liquid passes through the filter medium 32 from outside to inside, and impurities in the liquid are removed in the process. The liquid that has passed through the inside of the filter medium 32 passes through the holes 31 d formed in the inner tube 31 and flows out to the inside of the inner tube 31.

The liquid after filtration flows out to the outside of the filtration device 1 from the inside of the inner tube 31 via the outflow port 22. Note that between the filter element 30 and the inner tube 31, and between the filter element 30 and the lid member 20 are liquid-tightly closed by the sealing members 41, 42, respectively. Therefore, the liquid before filtration does not penetrate into the inside of the inner tube 31.

The filtration of the liquid gradually decreases a filtration capacity of the filter medium 32. Thus, the filter element 30 is replaced periodically or as needed. A procedure of the replacement will be described below.

First, the external thread portion 24 and the internal thread portion 15 are unscrewed to disassemble the filter case 10 and the lid member 20. As a result, the plate 34 of the filter element 30 is exposed. By pulling up the plate 34, the filter element 30 is removed from the inner tube 31. At this time, the use of the projections 34 d as gripped portions facilitates handling of the filter element 30.

After that, the new filter element 30 is then inserted into the filter case 10. Because the protruding portion 31 c is formed in the inner tube 31, the insertion of the filter element 30 in which the recessed portion 33 c is formed inserts the protruding portion 31 c into the recessed portion 33 c, and the filter element 30 is pushed until the surface 33 e abuts on the upper surface of the flange portion 31 b.

When the filter element 30 is inserted into the filter case 10, the external thread portion 24 and the internal thread portion 15 are screwed to join the filter case 10 and the lid member 20 together. In the process of screwing the external thread portion 24 and the internal thread portion 15, the fitting cylinder 25 is inserted into the tubular portion 34 c, and the projection 34 d is inserted between the rib 25 a and the rib 25 a. When the external thread portion 24 and the internal thread portion 15 continue to be screwed together, by pressing the projections 34 d by the ribs 25 a, the fitting cylinder 25 is inserted into the inside of the tubular portion 34 c while the lid member 20 and the filter element 30 rotate with respect to the inner tube 31.

Because the projection 34 d is inserted into the notch 25 d between the rib 25 a and the rib 25 a, the external thread portion 24 and the internal thread portion 15 can be screwed together until the distal end 34 e of the tubular portion 34 c abuts on the flange portion 25 b. Thus, the replacement of the filter element 30 ends.

Here, assume a case in which a filter element as a non-genuine product other than the filter element 30, which is a genuine product, is attached to the filter case 10 and the lid member 20. For example, in a case where the recessed portion 33 c is not formed on the filter element of the non-genuine product, the surface 33 e abuts on the protruding portion 31 c and the filter element of the non-genuine product cannot be inserted up to the correct position. As a result, the external thread portion 24 and the internal thread portion 15 cannot be screwed together, and the filtration device 1 cannot be used.

For example, in a case where a depth of the recessed portion 33 c formed on the filter element of the non-genuine product is insufficient or in a case where the projections 34 d are not formed on the filter element of the non-genuine product, the external thread portion 24 and the internal thread portion 15 can be screwed only up to the middle, and the filtration device 1 cannot be used.

For example, assume a case in which, instead of the projections 34 d of the filter element 30 as the genuine product, a flange having a substantially circular plate shape is provided on the filter element as the non-genuine product. In a case where such a filter element of the non-genuine product is inserted into the filter case 10, the rib 25 a contacts the flange during the process of screwing the external thread portion 24 and the internal thread portion 15, and the external thread portion 24 and the internal thread portion 15 cannot be screwed together, thereby failing to assemble the filtration device 1. In addition, also in the case where the notches 25 d are not formed on a lid member not a genuine product (a rib having a substantially cylindrical shape is formed), the rib having the substantially cylindrical shape contacts the projection 34 d and the external thread portion 24 and the internal thread portion 15 cannot be screwed together, thereby failing to assemble the filtration device 1.

According to the present embodiment, it is possible to reliably prevent the use of the filter element other than the filter element 30 as the genuine product, that is, the filter element of the non-genuine product.

Note that while the filtration device 1 includes the first imitation attachment prevention structure 50 and the second imitation attachment prevention structure 51 in the present embodiment, the filtration device 1 only needs to include the first imitation attachment prevention structure 50 or the second imitation attachment prevention structure 51.

In addition, while the filtration device 1 includes the four ribs 25 a and the four projections 34 d in the present embodiment, at least one projection 34 d only needs to be provided. In the case of one projection 34 d, it is only necessary that the two ribs 25 a are provided at positions where the projection 34 d is sandwiched and the projection 34 d is inserted into the notch 25 d between the two ribs 25 a. Additionally, in the case of one projection 34 d, instead of the two ribs 25 a, one rib having a substantially cylindrical shape with the notch 25 d to which the projection 34 d fits may be provided. However, to make manufacturing of the non-genuine product difficult and to reliably prevent the use of the component other than the genuine product, providing the plurality of ribs 25 a, notches 25 d, and projections 34 d is preferred. Additionally, the plurality of ribs 25 a, notches 25 d, and projections 34 d are preferably provided uniformly. For example, the six ribs 25 a, the six notches 25 d, and the six projections 34 d may be provided at every approximately 60 degrees. In this manner, by providing the plurality of ribs 25 a, notches 25 d, and projections 34 d and disposing these members uniformly, assembly properties can be improved while the use of the component other than the genuine product is prevented.

Second Embodiment

In the present embodiment, while the first imitation attachment prevention structure 50 includes the ribs 25 a and the projections 34 d, and the ribs 25 a are provided along the outer circumferential surface of the tubular portion 34 c, the configurations of the ribs 25 a, the tubular portion 34 c, and the projections 34 d are not limited to these configurations.

FIG. 9 is a diagram illustrating an overview of a first imitation attachment prevention structure 50A included in a filtration device 2. The first imitation attachment prevention structure 50A includes ribs 25 a-1, a tubular portion 34 c-1, and the projections 34 d. A notch 25 d-1 into which the projection 34 d is inserted is provided between the ribs 25 a-1 and the ribs 25 a-1. The projections 34 d are provided on a distal end of a small-diameter portion 34 g. The small-diameter portion 34 g is provided on a distal end side of the tubular portion 34 c-1, and has an outer diameter smaller than that of a large-diameter portion 34 i provided on a base side of the tubular portion 34 c-1.

The tubular portion 34 c-1 has a planar portion 34 h, and the planar portion 34 h is formed between the small-diameter portion 34 g and the large-diameter portion 34 i. When a lid member 20A is attached to a plate 34A, the projections 34 d are inserted into the notches 25 d-1, the ribs 25 a-1 are provided along the outer circumferential surface of the small-diameter portion 34 g, and distal ends of the ribs 25 a-1 are adjacent to the planar portion 34 h.

FIG. 10 is a cross-sectional view on a surface P in FIG. 9 . FIG. 10 illustrates a state seen from a front side of the paper of FIG. 9 . In plan view, the position of the rib 25 a-1 overlaps with the position of the tubular portion 34 c-1. Additionally, a recessed portion 25 e is formed on the rib 25 a-1 such that the position of the rib 25 a-1 overlaps with the position of the small-diameter portion 34 g and a part where the rib 25 a-1 overlaps with the small-diameter portion 34 g is cut out in plan view. Thus, when the lid member 20A is attached to the plate 34A, a bottom surface 25 f of the recessed portion 25 e is adjacent to the distal end of the small-diameter portion 34 g, and the lid member 20A is pushed to the plate 34A up to a position where the distal end of the rib 25 a-1 is adjacent to the planar portion 34 h.

Here, assume a case where a non-genuine product in which the recessed portions 25 e are not provided on the ribs 25 a-1 is attached to the filter case 10 (see FIG. 9 ). When the recessed portion 25 e is not provided, the distal end of the rib 25 a-1 abuts on the distal end of the small-diameter portion 34 g and the lid member 20A cannot be pushed up to the position where the distal end of the rib 25 a-1 is adjacent to the planar portion 34 h, and therefore the lid member 20A cannot be attached to the filter case 10. In contrast, in the filtration device 2, the ribs 25 a-1 and the tubular portion 34 c-1 are formed so that the positions of the ribs 25 a-1 and the position of the tubular portion 34 c-1 overlap in plan view, and the recessed portions 25 e are provided such that the ribs 25 a-1 do not contact the small-diameter portion 34 g. Thus, the lid member 20A can be pushed up to the position where the distal end of the rib 25 a-1 is adjacent to the planar portion 34 h.

As described above, according to the present embodiment, the use of the filter element or the lid member of the non-genuine product can be reliably prevented. In addition, since the components are not increased, the assembly properties are not reduced.

Note that in the present embodiment, the second imitation attachment prevention structure 51 may be omitted. The filtration device 2 may only include the first imitation attachment prevention structure 50A or may include the first imitation attachment prevention structure 50A and the second imitation attachment prevention structure 51.

Modifications of Second Embodiment

While the second embodiment uses the tubular portion 34 c-1 with the small-diameter portion 34 g formed on its distal end, the small-diameter portion 34 g may be omitted. FIG. 11 is a diagram illustrating an overview of the modification in which the small-diameter portion 34 g is not used. A recessed portion 25 g is formed on a rib 25 a-2 such that a position of the rib 25 a-2 overlaps with the position of the tubular portion 34 c and a part where the rib 25 a-2 overlaps with the tubular portion 34 c is cut off in plan view. Thus, when a lid member 20B is attached to the plate 34, a bottom surface 25 h of the recessed portion 25 g is adjacent to the distal end of the tubular portion 34 c, and the lid member 20B is pushed to the plate 34 up to a position where the distal end of the rib 25 a-2 is adjacent to the plate-like portion 34 a.

In contrast, assume a case where a non-genuine product in which the recessed portion 25 g is not provided is attached to the filter case 10 (see FIG. 9 ). In a case where the recessed portion 25 g is not provided, the distal end of the rib 25 a-2 abuts on the distal end of the tubular portion 34 c, and the lid member 20B cannot be pushed up to a position where the distal end of the rib 25 a-2 is adjacent to the plate-like portion 34 a. As described above, in the present modification, the use of the filter element or the lid member of the non-genuine product can be reliably prevented, similarly to the second embodiment.

Note that, in the second embodiment, the shape is more complicated than that of the present modification. Thus, when the lid member or the filter element of the non-genuine product is processed and attempted to be attached to the filter case of the genuine product, processing the non-genuine product is difficult. Therefore, compared to the present modification, the second embodiment can more reliably prevent the use of the filter element or the lid member of the non-genuine product.

Third Embodiment

The third embodiment has a configuration in which a third imitation attachment prevention structure 52 is provided instead of the first imitation attachment prevention structure 50. FIG. 12 is a diagram illustrating an overview of the third imitation attachment prevention structure 52 included in a filtration device 3.

A difference between the third imitation attachment prevention structure 52 and the first imitation attachment prevention structure 50A is presence/absence of the notches 25 d-1. The third imitation attachment prevention structure 52 includes the rib 25 a-2 and a tubular portion 34 c-2. The rib 25 a-2 is a substantially cylindrical rib substantially parallel to the insertion portion 25 c (see FIG. 2 ) and similar to the rib 25 a-1 except that notches are not formed. The tubular portion 34 c-2 is the similar to the tubular portion 34 c-1 except that the projections 34 d are not formed. The cross-sectional shape of the surface P in FIG. 12 is similar to that of FIG. 10 .

According to the present embodiment, the filtration device 3 including the third imitation attachment prevention structure 52 avoids the external thread portion 24 and the internal thread portion 15 (see FIG. 2 ) to be screwed together even when the filter element or the lid member of the non-genuine product is attempted to be attached to the filter case 10. As a result, the use of the filter element or the lid member of the non-genuine product can be reliably prevented.

Note that the filtration device 3 may include the second imitation attachment prevention structure 51 in addition to the third imitation attachment prevention structure 52. The filtration device 3 including the second imitation attachment prevention structure 51 and the third imitation attachment prevention structure 52 allows further reliably preventing the use of the filter element or the lid member of the non-genuine product. A cross-sectional shape of the surface Pin FIG. 12 may be similar to that of FIG. 11 .

The embodiments of the invention are described above in detail with reference to the drawings. Specific configurations are not limited to the embodiments and also include changes in the design or the like within a scope that does not depart from the gist of the invention. A person skilled in the art can easily modify, add, and convert each element in the above embodiments as appropriate.

In addition, the term “substantially” in the present invention is a concept not only including the case of being strictly the same, but also including deviations and modifications to an extent that the deviations and modifications do not result in a loss of identity. For example, the term “substantially same” is not limited to the case of being strictly same, but is a concept that includes an error to the extent not losing sameness. Further, for example, when simply expressed as “same,” it also includes a case of substantially same, in addition to the case of being strictly same. In addition, in the present invention, the term “near” means to include a region in a certain range (the range can be determined as desired) near a reference position. For example, “in the vicinity of A” refers to a region of a range near A, and is a concept indicating that A may or may not be included.

REFERENCE SIGNS LIST

-   1 Filtration device -   10 Filter case -   11 Bottom surface -   12 Hole -   12 a Internal thread portion -   13 Side surface -   14 Opening end -   15 Internal thread portion -   20 Lid member -   21 Inflow port -   22 Outflow port -   23 Attachment portion -   24 External thread portion -   25 Fitting cylinder -   25 a, 25 a-1, 25 a-2 Rib -   25 b Flange portion -   25 c: Insertion portion -   25 d, 25 d-1 Notch -   25 e, 25 g: Recessed portion -   25 f Bottom surface -   30 Filter element -   31 Inner tube -   31 a Tubular portion -   31 b Flange portion -   31 c Protruding portion -   31 d Hole -   31 e Protruding portion -   31 f External thread -   31 g Outer circumferential surface -   32 Filter medium -   33, 34 Plate -   33 a Plate-like portion -   33 b Hole -   33 c Recessed portion -   33 d Tubular portion -   33 e Surface -   34 a Plate-like portion -   34 b Hole -   34 c, 34 c-1, 34 c-2 Tubular portion -   34 d Projection -   34 e Distal end -   34 f Inner circumferential surface -   34 g Small-diameter portion -   34 h Planar portion -   40 Indicator -   41, 42: Sealing member -   50, 50A First imitation attachment prevention structure -   51 Second imitation attachment prevention structure -   52 Third imitation attachment prevention structure 

The invention claimed is:
 1. A filtration device comprising: a filter element that includes a filter medium, a first plate, and a second plate, the filter medium having a hollow substantially cylindrical shape with openings at both ends, the first plate covering the opening at an upper end of the filter medium, the second plate covering the opening at a lower end of the filter medium; a filter case having a bottomed substantially cylindrical shape that is internally provided with the filter element; and a lid member covering an opening at an upper end of the filter case, wherein; the filter element includes an inner tube inserted into a hollow portion of the filter medium; the second plate has a hole into which the inner tube is inserted; the inner tube includes a flange portion and a protruding portion, the flange portion having a substantially circular plate shape is disposed on a lower side of the second plate, and the protruding portion that protrudes upward from the flange portion; a recessed portion into which the protruding portion is inserted is formed on a surface on a lower side of the second plate; the first plate includes a first tubular portion having a substantially cylindrical shape, and the first tubular portion protrudes toward the lid member with the filter element inserted into the filter case; the lid member includes a second tubular portion and ribs, and the second tubular portion is configured to be inserted into a hollow portion of the first tubular portion; when the second tubular portion is inserted into the first tubular portion, the ribs are disposed along an outer circumferential surface of the first tubular portion; a position of the first tubular portion overlaps with a position of one of the ribs in plan view; a second recessed portion is formed on the one of the ribs such that a part where the one of the ribs overlaps with the first tubular portion is cut out; and with the lid member attached to the first plate, a bottom surface of the second recessed portion is adjacent to a distal end of the first tubular portion.
 2. The filtration device according to claim 1, wherein the first tubular portion includes a small-diameter portion provided on a distal end side and a large-diameter portion provided on a base side, the small-diameter portion has an outer diameter smaller than an outer diameter of the large-diameter portion, the second recessed portion is formed on the one of the ribs such that a position of the one of the ribs overlaps with a position of the small-diameter portion and a part where the rib overlaps with the small-diameter portion is cut out in plan view, and with the lid member attached to the first plate, the ribs are disposed along an outer circumferential surface of the small-diameter portion and distal ends of the ribs are adjacent to a planar portion formed between the small-diameter portion and the large-diameter portion.
 3. The filtration device according to claim 1, wherein the first tubular portion includes projections protruding outward in a radial direction, the ribs are provided with notches, and with the lid member attached to the first plate, the second tubular portion is inserted into the first tubular portion and the projections are inserted into the notches.
 4. The filtration device according to claim 1, wherein the protruding portion has a substantially cylindrical shape.
 5. The filtration device according to claim 2, wherein the first tubular portion includes projections protruding outward in a radial direction, the ribs are provided with notches, and with the lid member attached to the first plate, the second tubular portion is inserted into the first tubular portion and the projections are inserted into the notches.
 6. The filtration device according to claim 2, wherein the protruding portion has a substantially cylindrical shape.
 7. The filtration device according to claim 3, wherein the protruding portion has a substantially cylindrical shape.
 8. The filtration device according to claim 5, wherein the protruding portion has a substantially cylindrical shape. 